Fast Radio Bursts the briefest of moments, some dead stars can flash brighter than their entire galaxy (in Radio light) and then live to do it again and again. It’s time for an update on fast radio bursts, a phenomenon we’ve only known about for a few decades. In this time astronomers have learned a tremendous amount them. They’re not solved, but we’re getting closer!
Show Notes
- What Are Fast Radio Bursts (FRBs)?
- Discovery
- Nature of FRBs
- How Do We Detect FRBs?
- CHIME Telescope
- Microlensing and Scintillation
- Current Theories on FRBs’ Origins
- Leading Candidate: Magnetars
- Other Hypotheses
- The Odd Case of FRB 1809-16
- Unlike most FRBs, this one repeats every 16.35 days, suggesting an orbital pattern.
- Its location in a star-forming region strengthens the magnetar theory.
- Future Research & Discoveries
- Upcoming Telescopes & Observatories
- Exciting Possibilities
Transcript
Fraser Cain: AstronomyCast, Episode 748, New Insights into Fast Radio Bursts. Welcome to AstronomyCast, our weekly facts-based journey through the Cosmos, where we help you understand not only what we know, but how we know what we know.
I’m Fraser Cain, I’m the publisher of Universe Today. With me as always is Dr. Pamela Gay, a Senior Scientist for the Planetary Science Institute and the Director of CosmoQuest. Hey Pamela, how are you doing?
Dr. Pamela Gay: I am doing well. We had massive storms over the weekends. My studio is a hot mess because we all hid down here, but everything here is fine.
Heart goes out to everyone in Alabama. They got it much, much worse than we did. We just have downed tree lands.
Spring is here.
Fraser Cain: Yeah. Spring is here. So I had a week, which was, you know, we weren’t here last week, that was because I was dealing with my server.
We were here last week. We weren’t here two weeks ago. Two weeks ago.
Right.
Dr. Pamela Gay: You were still dealing with your server last week.
Fraser Cain: Yeah. Yeah. So I guess, right.
So last week was before I’d sent out the video explaining what had happened and sort of what we needed. And now the response has been overwhelming, that people have just jumped to our assistance and the gap that I needed to fill for astronomy, sorry, astronomy, the gap I needed to fill for Universe Today, you know, from the shortfall of the advertising has been filled. So we are set.
You know, we have the budget to continue on with all of the writing, with all of the team that we even have. I think we’ll have budget to bring on new writers if we need to. And it’s just, it’s so surreal to look at the Universe Today website and it just has no ads.
It has nothing. It’s just, it’s just gorgeous. It’s gorgeous.
Yeah.
Dr. Pamela Gay: Yeah. Yeah. You need to do archives back though.
Fraser Cain: I was trying to find old posts and couldn’t. I’m at 2013. So I’m bringing the years back one at a time very carefully because each one is injecting a thousand new articles into the database and then the site kind of freaks out for an hour after I do that.
So I’m doing this one year per day. And so I’m still, still catching up. But it’s funny because I still have this very instinctive, like, I’ve got to be careful about the topics that we choose.
I’m like, no, I don’t, I don’t care anymore. And so, and so the, the new cycle for James Webb was released. So all of the stuff they’re going to be doing for cycle four, all of the planetary stuff, all of the, and so I was, I was talking to Matt, who’s going to write a story about this.
I’m like, let’s do like a four part series on cycle four. And he says, actually, I think it, I think it needs five. I’m like, done.
So we’re doing a five part deep dive into all of the different science that’s planned for, for Webb for the upcoming next cycle. So one whole thing about exoplanets, one whole thing about cosmology, one whole thing about Milky Way stuff and stuff in the solar system and, and so on. Yeah.
Yeah. Yeah. And it’s great.
Cause it’s just like, this is what I want to see. This is what I want to know. I want us to investigate this.
And so we, I chewed up, uh, 30 stories from the LPSC meeting in, um, The Venus news that came out, Houston, it was in Houston. Yeah. Yeah.
So yeah, the, the, there’s, there’s mission ideas. There’s incredible new stuff that’s, that’s, and nobody is reporting on this because there’s no press releases. I was so frustrated with that.
Because everybody’s uncertain. Well, we are certain we’re moving forward. So I’ve got probably 30 stories coming out just about this one meeting, new mission ideas.
Look, we’ve got a couple of them already on the site. Uh, the thing called the Night Hawk, which is a, uh, beefed up version of the, um, ingenuity space helicopter that would go to Noctis Labyrinthus and fly at a hundred meters and carry a five kilogram payload and, and circumnavigate the whole area. So we’ve got a lot of really cool stories.
So anyway, thank you everybody who responded and helped us make this reality. And I will pay back your kindness in a fire hose of ad free space news. Enjoy.
It’s time for an update on fast radio bursts and phenomena that we’ve only known about for a few decades. In this time, astronomers have learned a tremendous amount about them. They’re not solved, but we’re getting closer and we’ll talk about it in a second, but it’s time for a break and we’re back.
So we last covered fast radio bursts. I just checked the, uh, the site was episode four 75, which that’s 300 ish episodes ago, which is six, six, eight years old. Six years.
We do about 40 episodes a year.
Dr. Pamela Gay: Yeah. Something like that.
Fraser Cain: Yeah. It’s time for an update on fast radio bursts. What have we learned?
I guess, well, let’s go back first and let’s just like set the mystery, which is like, how did we first even find out about fast radio bursts?
Dr. Pamela Gay: It was a student. So back in 2007, uh, David Lohemar, and I’m sure I mispronounced that. And I’m very sorry if you are out there human, you do lovely research.
Um, and he was going through looking at pulsar data and in the midst of the pulsar data, saw this super weird flash, brought it to the attention of his advisor. They confirmed it was real. And since then people have been finding them both in archival data and then finding them in real time, including with, they did a purpose built radio array chime just to study these things.
So since 2007, we went from a student going, Hey, there’s this weird thing in the archive to now building telescope arrays that have multiple systems scattered about Canada and the United States that are trying to pinpoint what they are, where they are and exactly what they do and do not do in the sky.
Fraser Cain: I mean, to be fair, time wasn’t purpose built for this. It’s more designed to, it was originally designed to observe the sort of radio afterglow of the big bang, the early universe, but it, but it’s like perfectly capable for this job.
Dr. Pamela Gay: And so to it that, right. Yeah.
Fraser Cain:Yeah. And most of the discoveries about fast radio bursts have come from time, which is this awesome snowboard half pipe, like a radio telescope here in British Columbia. Um, yeah, I hear it’s a sick ride.
If you, you know, you catch the, get the snows, right. Um, so, okay. So we’ve got these, this, this weird mystery.
And, and so here we are now 20 plus years after that, or not almost 20 years after that first discovery. And like, what have we learned in this intervening time?
Dr. Pamela Gay: So the first thing that we’re able to figure out is to get something that exists for that brief a moment in time. So the longest of these are three seconds ish. Most of them are millisecond in time.
That means they have to be super small because light takes time to move and the larger, the thing giving off the light, the longer, the amount of duration it has to have for the light from the entire object to get to us. So the fact that they exist for such a brief moment in time means they have to be measured in hundreds of kilometers or less. So that instantly implied, this has to be something that’s going on with a very tiny object or taking place in the environments of an object where the part of the environment that is doing the thing that is being done must be very small.
Fraser Cain: It’s funny. Like originally there was a lot of these questions of, are these just reflections coming from earth? Is this something that’s happening within the solar system?
And over time, they’re at least able to confirm, no, no, these things are extra galactic. And then once, as you say, once you get extra galactic, then whatever it is has got to be releasing a ludicrous amount of energy, but in the radio spectrum. So you’re not getting this gamma ray burst where the telltale signature of a star going boom or two neutron stars colliding with each other, you’ve got this thing that is sending out this weird radio blast, which is a colossal amount of energy, but without all of the other stuff.
And at random times, you’re not getting this repeating thing like we see with pulsars. You’re not getting the radio, but also some kind of visible afterglow that you see with supernova and other things. You just get this random flash of a ludicrous amount of radio energy, and then mostly you don’t see it anymore.
So how did astronomers start to really chip away at this problem?
Dr. Pamela Gay: So the first thing was that lack of gamma rays that you mentioned is hugely important because when we start thinking about what creates light and is tiny, the first thing you go to is neutron stars. We had in 2004 this amazing moment where a magnetar on the other side of the Milky Way’s supermassive black hole, so on the other side of the core of the galaxy, decided it was going to rearrange its magnetic field, and it released a massive gamma ray burst that went through the sides of space telescopes and saturated the detectors. And so we know that magnetars can do these super brief, massive amounts of energy across the entire electromagnetic spectrum, but we don’t see gamma rays associated with these fast radio bursts.
And then we realized, okay, so most of the ones that we’re seeing, we’re only catching one at a time. So like one goes off here, silence. One goes off over here, silence.
But occasionally, just occasionally, we will get these repeaters that don’t repeat with any pattern we’ve been able to figure out. So that was new.
Fraser Cain: But at least they give us the dignity of flashing from the same location multiple times.
Dr. Pamela Gay: And then, because the universe likes to confuse us, there is FRB fast radio burst 1809-16. So 2018, September 16th.
Fraser Cain: Wait, you know what? This is exciting. We need to take another break.
Dr. Pamela Gay: Okay.
Fraser Cain: And we’re back. All right. After that cliffhanger, tell us about the fast radio burst.
Dr. Pamela Gay: So there’s FRB 1809-16, and we were able to identify where it is. It’s in a star forming region of a spiral galaxy. And this one, because it was determined to be different, repeats every 16.35 days. So we have one FRB, one fast radio burst, that for reasons we can only assume have to do with orbital motion maybe, it repeats every 16.35 days. So what do we know? Up until recently, we’re going to have one more cliffhanger.
Up until recently, what we understood was they have to be tiny. And we know that because of how briefly they flicker and flare. Milliseconds.
Fraser Cain: They have to be extra galactic.
Dr. Pamela Gay: We have found some in our galaxy.
Fraser Cain: Okay, but they have to be outside of the solar system.
Dr. Pamela Gay: Yes, they have to be outside of the solar system. And we know some of them have cosmological distances. We know most of them don’t repeat that we have seen.
That doesn’t mean they haven’t repeated. It means we haven’t seen them repeat. We know most of the ones that repeat do it randomly.
We know there is one that repeats every 16.35 days. Plus or minus 0.15 for those keeping track. And up until recently, all of them that we had found and been able to identify the location, which is a pain with these radio sources, were in active galaxies, star-forming galaxies, near the cores of galaxies.
And we were associating them with areas that had very young stars, which is key. Because certain objects can only exist in star-forming regions, particularly magnetars. And so the thought was, these must be neutron stars that have recently formed, are fast rotating, have powerful magnetic fields.
The powerful magnetic fields being the key point. And something happens in the magnetic field that creates this massive release of energy. So, since we only find magnetars in areas that have had stars that recently died, that were massive, they have to be found in areas that are young and have star-forming regions.
So things that are less than millions to billions of years old, not ancient things, not dead things.
Fraser Cain: Right, because the biggest stars only die in millions of years. And so you’re going to have some star-forming region, all of the O’s and the B’s, they detonate within a few million years, and large stars leave neutron stars as their remnant, or black holes, but neutron stars. And then the neutron stars, when they’re freshly made, are spinning very quickly, and they’re the ones that turn into pulsars.
But also some subgroup, and this is a mystery for another episode, some subgroup turn into magnetars, and we don’t entirely know why.
Dr. Pamela Gay: There are a lot of papers that this is what my gut thinks is going to prove out to be true. There are multiple theories out there. The one that I’m liking the most is that when you get stellar mergers leading to neutron stars, that’s where you get the powerful magnetic fields.
But that’s just one of the many different explanations out there.
Fraser Cain: We just did a story about this, about the source of magnetars, that we’re pretty close. I think we called it like, so this is how you get magnetars. I mean, I’m going to try this.
Dr. Pamela Gay: I couldn’t find that one on your site. Yes, I saw that one when I googled it.
Fraser Cain: Yeah, so this is how you get magnetars. Stellar remnants, dynamo, supernova, differential rotation. Yeah.
Dr. Pamela Gay: Is that the binary star model for how to form them, where you have a supernova in a binary system?
Fraser Cain: There are so many cool theories. So they did, sorry, they did simulations, and the best fit is known as the Taylor-Spruit dynamo, which is well-known stellar objects involves a differential rotation of a stellar core. So stars don’t rotate, so it’s caused by a fast rotating core.
So the core and the surface have differential rotation. Right. And that the magnetar, that the supernova, that the supernova, that created the magnetar transfers angular momentum to its core, thus creating a differential rotation in the star.
And this then creates the burst of the magnetic field that power the x-rays and gamma rays that we observe from these stars. That’s the most recent, highest, I don’t know, one leading theory of how you get magnetars. But you know, like one possibility is you have a star eat another star, and then that sets up differential rotation inside the star that then leads to the magnetar.
But this is still an unsolved, and this is why I said this is an unsolved mystery. It could be that you had a binary star, and one of the stars went off, and that changed the rotation of the star, that it’s going a lot faster. But neutron stars are limited.
When you get a blue star, they’re really limited to about just shy of 1,000 rotations a minute.
Dr. Pamela Gay: So something weird has to happen to get the magnetic field, which is where interactions with something else, or I guess special supernovae that allow the core to have a different… Yeah, this is one of these things where our ability to understand the universe is held back by our lack of creativity at times.
Fraser Cain: But both of these, I mean, they’re clearly connected. Yeah. And both of them are on their last, like they can’t hide for much longer.
Both of them, new instruments, new observatories, new techniques are coming online, new theories, better models, and both will fall, I think, within our lives anyway. All right, you threatened that there might be another cliffhanger, and why don’t we go into that right now?
Dr. Pamela Gay: So it could…
Fraser Cain: Hold on. No, break. And we’re back.
Dr. Pamela Gay: All right. So all these cool theories on we have understood what these are, they are magnetars in star forming regions, was the excitement of the journal articles. And then a paper came out that had found a new magnetar clearly located in an ancient galaxy.
And there’d been a couple of others that were associated with probably the outskirts of a galaxy with globular clusters. And so suddenly we have to figure out how to explain having these things in ancient areas, in places without star formation, in places where no self-respecting magnetar has thus far been found and clearly identified.
Fraser Cain: Right.
Dr. Pamela Gay: So the question becomes, how do you get these things occurring in the outskirts of galaxies? And the answer to that was, well, globular clusters do have stars that collide. And maybe if you have stars that collide just right, you get magnetars.
So that is one straw that is being grasped at. And this raises the distinct possibility that we’re going to find fast radio bursts, just like gamma ray bursts and just like so many other things in the universe have multiple origins that more than one of the theories that we’ve looked at so far start to become true. And it’s interesting to look at all the different things that are being figured out.
Just at the very end of December, there were researchers at MIT that figured out using scintillation, which is how radio light can flicker as it passes through a medium, to figure out that the source of a fast radio burst is hundreds of kilometers likely from the surface. So this is part of the magnetic field that is creating this flicker or flash that we are seeing, again, milliseconds to three seconds in time. And so we’re figuring out where in the environment of a magnetar these could exist.
And we’re also finding that they can exist in star forming regions. They appear to be able to exist in the outskirts of galaxies, potentially in globular clusters.
Fraser Cain: And so to summarize, the most likely cause at this point, the one that if you were to have astronomers place their bets, is that fast radio bursts are coming from magnetars. The flash of radiation is coming from magnetic reconnection events around the magnetar in the same way that… So it’s not the surface.
It’s the magnetic field. Right, that flares. And that matches our observation of the sun.
And we get these solar flares. And the flares can be of differing strengths. They go in different directions.
And it’s really just how the magnetic field lines twist and tangle around the sun until they’re finally released in this burst of energy. But we see it in X-rays. We see it in gamma rays coming off of the sun.
We see it in invisible light. And yet, whatever is happening with the magnetar, the bulk of the photons are coming in the radio. And so we’re just not seeing the other glows.
Except occasionally that we do. And then, of course, how do you get magnetars? And that’s a whole separate question that is still a bit of a mystery.
And so I love that these are both… We know that they’re related, but both are kind of mysterious. And both will probably fall together once it’s been figured out.
Dr. Pamela Gay: And I love this idea that magnetars can exist primarily in star-forming regions, but maybe also in globular clusters that the universe finds so many different ways to create things.
Fraser Cain: Well, and I know you really like this idea of the blue stragglers in globular clusters, right? You get these blue stars where there should be no blue stars in these ancient clusters. And the only explanation is that you have stars collide, which makes sense when you’ve got a bunch of stars buzzing around like busy bees in this ball that every now and then two of them are going to strike one another.
And then you get a new star that is either one star that’s had half of its surface torn off and added to the other star, or actually two stars have just directly collided and begun a new life as a fresh blue star again, which is really interesting.
Dr. Pamela Gay: The whole idea that stars never collide that they taught when we were young, totally wrong. Stars totally do collide. And this is how we get weird things sometimes.
It’s just one of the ways we get weird things. And this is why our show never needs to stop because astronomers keep rewriting the books. They keep discovering new things.
Every increase in our technology, whether it be the computational ability to do simulations or the observational ability to see the universe brings us new understanding. One of the things that came out of the Lunar and Planetary Sciences Conference last week is just the time scales that we sometimes have to wait for new things to get put into orbit. And this is why we will probably never retire.
Fraser Cain: Yeah, people ask us if we’re ever going to run out of topics, and the answer is absolutely not. That every time Pamela’s like, you know, can you got any suggestions for topics? I throw 30 her way without even blinking.
It’s easy every time. No problem. So yeah, the updates and the new things that are discovered.
And just think about the new observatories that are coming online. I mean, later this year, we’ll see Vera Rubin.
Dr. Pamela Gay: It put its camera on last week.
Fraser Cain: What? Oh, yeah. We’ve got the Extremely Large Telescope coming in 2028.
And each of these will give us a dramatic new view into the cosmos and overturn and both discover entirely new things, right? At some point, I guarantee we will be talking in about three years about a thing that happens in the universe that astronomers had absolutely no idea that this was an existence and that this was a thing. And it turns out this thing is incredibly important.
It gives valuable insights into the very nature of the cosmos itself. And yet here we are just completely ignorant to what that thing is. I look forward to that episode.
It’s awesome. Awesome. All right.
Thanks, Pamela.
Dr. Pamela Gay: Thank you, Fraser. And thank you so much to all of our patrons out there. You allow us to keep going no matter how bad the rest of the world may seem.
And thank you for giving us something joyful to do every week and to be able to pay our staff to do something joyful with us. This week, I would like to thank Sergey Manilov, Conrad Hailing, Tushar Nikhini, the Mysterious Mark, Hal McKinney, John Herman, Joanne Mulvey, Katie and Alyssa, Papa Hot Dog, Michael Hartford, Will Hamilton, Fairchild, just as it sounds, J.P. Sullivan, Galactic President, Scooper Star, McScoopsalot, Bogey Nat, or sorry, Bogey Nat, Sagi Kemmler, David Troge, Nick Boyd, William Andrews, Alexis Adam, Anis Brown, Astro Sets, Gold, Simon Parton, Claudia Mastroianni, Abraham Cottrell, Arctic Fox, Andrew Stevenson, Jim McGeehan, Gregory Singleton, David Gates, Georgie Ivanov, Yvonne Zegrev, Father Prax, Nate Detweiler, Dwight Ilk, Disastrina, Lou Zealand, Paul D.
Disney, Peter, Alex Rain, Reuben McCarthy, Astro Bob, Bob Zatsky, Alan Gross, Elliot Walker, Jeff McDonald, David Resetter, Travis C. Porco, Mike Heise, Jonathan Poe, RJ Basque, Demi Drake, Bob Crail, Tricor, Noah Albertson, Ryan Amari. Thank you all so very much.
Fraser Cain: Thanks, everyone. And we will see you next week.
Dr. Pamela Gay: Bye-bye.
Dr. Pamela Gay: AstronomyCast is a joint product of Universe Today and the Planetary Science Institute. AstronomyCast is released under a Creative Commons Attribution License. So love it, share it, and remix it.
But please credit it to our hosts, Fraser Cain and Dr. Pamela Gay. You can get more information on today’s show topic on our website, AstronomyCast.com. This episode was brought to you thanks to our generous patrons on Patreon.
If you want to help keep this show going, please consider joining our community at Patreon.com slash AstronomyCast. Not only do you help us pay our producers a fair wage, you will also get special access to content right in your inbox and invites to online events. We are so grateful to all of you who have joined our Patreon community already.
Anyways, keep looking up. This has been AstronomyCast.